The disclosure of U.S. Pat. No. 4,449,073, issued May 15, 1984 is hereby incorporated by reference in this application.
This invention relates to airport runway approach monitoring systems that typically employ a series of sequentially activated strobe lamps for visually assisting aircraft landings. In the above-mentioned U.S. Pat. No. 4,449,073 such a system is described. It includes an oscillator driven counter that generates clock pulses to produce trigger signals for sequentially energizing the runway strobe lamps. The strobe lamp operations generate corresponding return pulses that are compared with the oscillator pulses and a fault signal is generated whenever there is no return pulse in response to a trigger pulse. A fault indication is provided at a central location after the occurrence of a predetermined number of fault signals in a predetermined time period.